PROBLEMS 1.1 Radiation energy spectra can be categorized into two main groups: t

Question

PROBLEMS 1.1 Radiation energy spectra can be categorized into two main groups: those that consist of one or more discrete ener- gies (line spectra) and those that consist of a broad distribution of energies (continuous spectra). For each of the radiation sources listed below, indicate whether "line" or "continuous" is a better description: nucleus with mass number 210 if the Q-value of the decay is 5.50 MeV 1.4 What is the lowest wavelength limit of the X-rays emit- ted by a tube operating at a potential of 195 kV? (a) Alpha particles. (b) Beta particles. (c) Gamma rays. (d) Characteristic X-rays. (e) Conversion electrons. (f) Auger electrons. (g) Fission fragments. (h) Bremsstrahlung. (i) Annihilation radiation 1.5 From a table of atomic mass values, find the approxi mate energy released by the spontaneous fission of 235U into two equal-mass fragments. 1.6 Calculate the specific activity of pure tritium (3H) with a half-life of 12.26 years. 1.7 What is the highest energy to which doubly ionized heli- um atoms (alpha particles) can be accelerated in a de accel- erator with 3 MV maximum voltage? 1.8 What is the minimum gamma-ray energy required to produce photoneutrons in water from the trace heavy water content? 1.2 Which has the higher energy: a conversion electron from the L shell or from the M shell, if both arise from the same nuclear excitation energy? 1.3 By simultaneously conserving energy and momentum, find the alpha-particle energy emitted in the decay of a 1.9 By simultaneously conserving energy and momentum calculate the energy of the neutron emitted in the forward direction by a beam of 150 keV deuterons undergoing the D-T reaction in a tritium target.

Explanation / Answer

1.1

1.2 M Shell

1.3

Q- value of the reaction results in KE of the output products, alpha- particle and the dauther nucleus.

daughter nuclues mass number A = 212 -4 = 208

beforce the decay the nucleaus is at rest and the total momentum is 0

after the decay let V be the speed of the duather nuclues and v that of alpha

conserving the momentum after decay

208*V = 4*v

V = v/52

KE of dauther nucleus = 208*V2 /2

                     alpha        = 4 * v2/2

conserving the energy

104 V2 + 2v2 = 5.6 Mev

replace V with v

v2/26 + 2v2 = 5.6

energy of alpha particle = 0.5* 4v2 = 2v2 = 2*5.6*26/53 = 5.49 Mev

1.4

The lowest wavelength limit if the X-ray emmited is = (h*c)/(q*V) = [(6.626 x 10-34) (3 x 108)] / [(1.60 x 10-19) (195 x 103)] = 6.37 x 10-12 m = 0.0637 A

1.5

fission of 235U into two equal mass fragments gives two-two nuclides with mass number 117 and 118.

Mass numbers 117 and 118 are 117Sn50, and 118Sn50, their masses being 116.902956 and 117.901609 amu respectively.

The mass of 235U is 235.043924 amu.

The difference in mass =235.043924 -(116.902956 + 117.901609) = 0.2394 amu

We know lhal 1 amu = 931.5 MeV

So,
0.2391 amu * (931.5 MeV) / (1 amu) = 223.00 MeV.

1.6

specific activity=(ln2 x NA)/ (T1/2*m)

NA=avogardo number=6.023x10^23

T1/2=12.26y

mass ,m=3

S=1.32x10^16/12.26*3

=3.58x10^14 Bq/gram

Radiation Source Line Continuous a) Alpha particles YES b) Beta particles YES c) Gamma rays YES d) Characteristic x-rays YES e) Conversion electrons YES f) Auger electrons YES g) Bremsstrahlung YES h) Annihilation radiation YES

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